1. Field of the Invention
The present invention relates to an apparatus for the delivery of materials onto a beam, wherein the tension of the warp sheet being delivered and the delivery angle of the warp is controlled.
2. Description of the Prior Art
In conventional systems for delivering a warp sheet onto a beam, such as warping sheets of yarns on a loom beam, yarn is fed through a creel to a delivery roll and delivered onto the beam. Control of the tension and angle of the warp sheet being fed onto the beam was accomplished by bringing the delivery roll close to the beam, providing maximum contact and hence control of the warp sheet. U.S. Pat. No. 4,819,310 shows such an apparatus. This device provides good control over the tension of the warp sheet when the width of the sheet is small and the diameter of the pickup beam is large, as in traditional silk system warpers.
Today, however, large section beamers are used to densely pack large warp sheets, often containing yarns of virtually zero elasticity, onto small diameter beams. Section beamers are capable of running significantly greater lengths of yarn onto the beam, resulting in a much greater diameter of the wound beam. Higher tension is required to reduce the number and degree of slack ends and to more densely pack yarn onto the beam. This is particularly important in the yarns of virtually zero elasticity, such as glass, Kevlar or Nomex.
In conventional warper systems the delivery roll is positioned close to the pickup beam and able to move laterally with respect to the beam to control the tension and delivery angle of the warp. Conventional systems cannot be used effectively in today's large section beamers due to the use of yarns of low elasticity, great variation in the delivery angle based on the beam diameter and the need for higher tension to more densely pack yarn onto the beam.
Systems have therefore developed in which the delivery roll is spaced apart from the pickup beam to reduce these problems. These newer systems can accommodate the higher tension requirements of large section beamers. Also, the delivery roll can be wider than the pickup beam, allowing the width of the warp sheet to be adjusted during winding. Spacing the delivery roll away from the pickup beam also allows an operator to more easily observe the warp sheet and detect defects. However, these systems have the substantial disadvantage of great variations in the tension of the warp sheet, due to variations in the delivery angle of the sheet being delivered onto the pickup beam.
An example of such a system used in the prior art is shown in FIG. 1. Warp sheet 1 is fed to calendar roll 8 and over delivery roll 2 and delivered onto pickup beam 3. As warp sheet 1 is fed onto pickup beam 3 the pickup beam diameter 4 increases outward toward pickup beam flange 5. This increase in diameter causes the delivery angle of the sheet to change by an angle .theta..sub.1 as warp sheet 1 moves from position 6 to position 7. The change in delivery angle .theta..sub.1 causes variations in the sheet tension producing fluctuation in the density of yarn packed onto the pickup beam. When using yarns of low elasticity changes in density can result in great damage to the yarn when it is wound off the beam. The variation in delivery angle .theta..sub.1, will also cause the warp sheet 1 to apply pressure to delivery roll 2 resulting in a pinching action of delivery roll 2 against calendar roll 8. This can cause severe damage to the warp sheet and possibly the warping system itself.